If you want to get your head spinning, read the rules governing no-thumb bowling, specifically the ball drilling rules.
You have to feel for those at the United States Bowling Congress charged with coming up with rules that fairly govern all situations!
The newest rules, which I detailed in this story, were enacted for the 2016 U.S. Open. They presumably stemmed from the growing popularity of “Triangle” or “WiFit” (aka “Duo”) grips that allow no-thumb...